How many electrons in calcium have l = 0 ?

Options

A. 6
B. 8
C. 10
D. 12

Answer

To determine how many electrons in calcium have an azimuthal quantum number (l) equal to 0, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Atomic Number of Calcium**:
- Calcium (Ca) has an atomic number of 20, which means it has 20 electrons.

2. **Write the Electronic Configuration**:
- The electronic configuration of calcium is:
\[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 \]

3. **Understand the Azimuthal Quantum Number (l)**:
- The azimuthal quantum number (l) describes the shape of the orbital.
- For s orbitals, l = 0.

4. **Identify the Orbitals with l = 0**:
- The only orbitals that have l = 0 are the s orbitals.
- In the electronic configuration of calcium, the s orbitals are:
- \(1s^2\) (2 electrons)
- \(2s^2\) (2 electrons)
- \(3s^2\) (2 electrons)
- \(4s^2\) (2 electrons)

5. **Count the Electrons in the s Orbitals**:
- Now, we sum up the electrons in all the s orbitals:
\[ 2 (from \, 1s) + 2 (from \, 2s) + 2 (from \, 3s) + 2 (from \, 4s) = 8 \, electrons \]

6. **Conclusion**:
- Therefore, the total number of electrons in calcium that have l = 0 is 8.

### Final Answer:
The number of electrons in calcium that have l = 0 is **8**.